In₂O₃/Bi₂S₃ S-scheme Heterojunction-Driven Molecularly Imprinted Photoelectrochemical Sensor for Ultrasensitive...

Florfenicol (FF) raises significant human health and environmental concerns due to its toxicity to the hematology system and the potential spread of antibiotic-resistant genes. Here, a highly sensitive molecularly imprinted photoelectrochemical (PEC) sensor, featuring an In₂O₃/Bi₂S₃ S-scheme heterojunction, is proposed to detect FF without an external voltage supply. Compared with conventional II-type heterojunctions, S-scheme heterojunctions efficiently promote carrier separation and enhance the redox capability of the photocatalytic system. This allows more dissolved O₂ and H₂O molecules to participate in the redox reaction, resulting in an amplified and stabilized photocurrent response. The electron transfer in the S-scheme heterojunction is confirmed via electron spin resonance (ESR). With the molecular imprinting technique, this PEC platform exhibits exceptional selectivity, wide linear range (1.0 × 10^-4-1.0 × 10⁴ ng mL^-1), low detection limit (6.4 × 10^-5 ng mL^-1), and applicability in real milk and chicken samples. This work not only showcases a PEC platform for accurately and portably detecting drugs but also proposes a viable approach for designing S-scheme heterojunctions in sensing analysis.